Nervous System and Spinal Nerve

Question 1

Motor vs sensory neuron

Answer 1

Motor: multipolar. Does the the action as a result of CNS signals
Sensory: UNi/pseudopolar. Relays signals from the outside world towards CNS for further processing

Question 2

Order of meninges from surface to interior

Answer 2

1. Dura (can actually hold a stitch…strongest one under the bone)
2. Arachnoid: Cannot hold a stitch. is dissectable. Pressed up against the Dura because of the pressure applied by CSF directly underneath it
3. CSF: Acts as shock absorber for the spinal cord
4. Pia matter: Runs directly along with spinal cord and brain (All of CNS). Cannot be dissected without damaging spinal cord tissue
5. Spinal Cord…don’t touch lol

Question 3

Foramen magnum

Answer 3

Huge opening in the skull. Leads directly to first vertebrate (which stacks to make vertebral canal that encompasses spinal cord)

Question 4

1. Where does spinal cord end?
2. What is it called, and what stems off of it
   Where do you do spinal tap?

Answer 4

1. L1-L2 intervertebral disk
2. Conas medullaris; Cauda equina (horse tail…collection of nerve roots)
3. L3-L4 intervertebral disk

Question 5

1. Amount of spinal nerves
2. Name the 4 regions of the spinal cords, the amount of spinal nerves in each, the amount of segments in each, and the amount of vertebrae in each

Answer 5

1. 31 PAIRS of them
2. Cervical: 8; 8; 7
3. Thoracic: 12; 12
4. Lumbar: 5; 5
5. Sacral: 5; 5
6. Very tip of the conas medullaris = coxagial nerve…1 pair

Question 6

1. Where does spinal cord end with respect to the vertebrae?

2. Where does the spinal cord end, with respect to the spinal cord segments?

Answer 6

1. Between vertebral bodies of L1-L2

2. Around coxagial/sacral level

Question 7

1. White matter
2. Grey matter
3. Ventral vs dorsal

Answer 7

1. Myelinated axons.
2. Not myelinated
3. Ventral horn: directs outside of the cord (motor neurons). Dorsal horn: directs info into the cord (sensory)

Question 8

Amount of cranial nerve pairs

Answer 8

12…they all come off the brain/brain stem

Question 9

Ventral and Dorsal root

Answer 9

Comes out ventral and spinal horn. Converses to make SPINAL NERVE (incredibly short segment, which branched off into ventral and dorsal rami)

Question 10

Dorsal root

Answer 10

Contains dorsal ganglia., which contains pseudounipolar/unipolar cell bodies (remember, it’s sensory)

Question 11

1. Consequences of cutting dorsal/ventral roots.
2. Consequence of cutting spinal nerve
3. Consequence of cutting rami

Answer 11

1. Cut dorsal: lose sensation. Cut ventral: gain paralysis (lose movement)
2. Cut spinal nerve: lose both.
3. Cut rami: lose both (remember, both sensory and motor pass through it so that you affect that particular side of the body)

Question 12

What are the only 3 things the dorsal rami innervate?

Answer 12

Zygapophyseal joints (facets) (vertebrate are linked together with this), True/intrinsic back muscles, skin on the back. ALL ELSE that is not innervated by cranial nerves is innervated by VENTRAL rami

Question 13

Dermatome

Answer 13

Slices of skin. maps sensory information. Belly button (Umbulicus): T10 spinal nerve!!!!! Always

Question 14

Dermatomal segments

Answer 14

Each of which are overlapped superiorly and inferiorly. If you are in T10 (central line), you will receive overlap from nerves from T9 and T11

Question 15

ANS

Answer 15

Conveys info from internal organs to CNS. Receives sensory, and CNS shoots out motor.

Question 16

SNS

Answer 16

Increase heartrate, increase breathing, dialate bronchus, start sweating, dialate pupils to take in more light, direct blood more to skeletal muscles and away from the gut

Question 17

ParaSNS

Answer 17

Opposite of ANS (lower heartrate, lower breathing rate, blood redircted to GI, start peristolsis, constrict pupils)

Question 18

Which is more rapid? SNS or ANS?

Answer 18

SNS

Question 19

Somatic motor neurons innervate:

Path taken:

Answer 19

Skeletal muscle

ONE motor neuron pathway from spinal cord

Question 20

Autonomic (Visceral) Motor Neurons:

Path Taken:

Answer 20

Smooth muscle (wall of hollow organs and the arteries), Cardiac Muscle, Glands
TWO motor neuron pathway from spinal cord (One cell body from the spinal cord. The second one located in the ganglia in the periphery. They are MOTOR. note that the ganglia in the dorsal root are SENSORY. Not motor)

Question 21

FOR PARASYMPATHETIC, Preganglionic Cell bodies Location vs Postganglionic Cell bodies Location

Answer 21

Pre: Brainstem or Sacral levels of spinal cord
Post: Terminal ganglia

Question 22

Are there any parasympatheitcs in the spinal nerves?

Answer 22

No.

Question 23

FOR SYMPATHETIC: Preganglionic vs post ganglionic wiring

Answer 23

Preganglionic cell bodies: Located in LATERAL horn (Between dorsal and ventral horn) of Spinal cord ONLY IN SEGMENTS T1 - L2
Postganglionic cell bodies: Located in PARAVERTEBRAL GANGLIA (Or Sympathetic Ganglia) in periphery

Question 24

White ramus communicans

Answer 24

Myelinated pathway that communicates with the paravertebral ganglion from ventral ramus Present from T1 - L2

Question 25

Grey ramus communicans

Answer 25

NOT myelinated. Goes back to the spinal nerve to ventral ramus. Present from T1 - L2

Question 26

SNS Synapses: Difference between Pre and post ganglionic axons

Answer 26

Pre: synapses with postganglionic cell bodies
Post: Synapses (Innervates) sweat glands, smooth muscle of blood vessles, and cardiac muscle

Question 27

How do we get sympathetic innervation distributed to sweat glands and blood vessels of the trunk of the body?

Answer 27

Remember that from T1 to L2 there are already sympathetic nerves there. Trunk covers T1 to L1, so you’re good. Will follow dermatomal segment. Distributes post ganglionic, sympathetic axons to the sweat glands